Electric discharge tube



Ap 1951 c. F. VEENEMANS 2,549,949

ELECTRIC DISCHARGE TUBE Filed Dec. 6, 1947 6 4 4 5 I l 9 n nn a 1 j t 4 I a 5 5 7 9 \LL /7 g 5 \f 2 g 9 Fly.

CFTVEENEMANS INVENTOR AGENT Patented Apr. 24, 1951 ELECTRIC DISCHARGE TUBE Cornelis Frederik Veenemans, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company,

trustee Hartford, Conn., as

Application December 6, 1947, Serial No. 790,096

In the Netherlands September 10, 1946 Section 1, Public Law 690, August8, 1946 Patent expires September 10, 1966 4 Claims.

The invention relates to electric discharge tubes wherein the bulb is closed by means of a base having contact members sealed in it, and to a method of manufacturing such tubes.

Attempts are made to minimize the dimensions of present-day discharge tubes as far as possible, so that the tolerances in the dimensions of bulb and base become smaller and smaller since the minimum permissible dimensions have to be observed as exactly as possible in order to avoid diiliculties. Moreover, since caps and the like are no longer used so that the seal has to assume a prescribed shape, it is no longer possible to work with an excess of glass because this would give rise to an irregular shape of the edges of the seal. Besides, a result thereof is that after bulb and base have been united the length of the bulb acquires an exactly determined constant value. In sealing bulb and base together, it is therefore necessary that an exactly determined pressure should be exerted on the bulb in order to ensure that the seal always acquires the same shape, that is to say that the edges of soft molten glass must be upset over a determined length. Even if the bulb and the base are united by means of glaze an exactly determined constant pressure is. necessary for obtaining a satisfactory seal. In the case of an excessive pressure the glaze is urged away with the result that between the surfaces required to be united glaze is no longer present so that a solid connection is not obtained. If the pressure is too small there exists the danger that the connection is not vacuum-tight and that the glaze insufficiently moistens the bulb portion intended to bear upon the base and consequently adheres unsatisfactorily.

In modern discharge tubes the electrode system is generally mounted on a base consisting, for example, of pressed glass whilst at the top it is provided with a centering member, for example of mica, by which the system is supported and centered with respect to the wall of the bulb. To that end the centering member generally exerts a resilient pressure on the wall of the bulb. Since upon displacement of this member the resilient parts thereof grate over the wall it is very dimcult to bring the bulb and the base with a determined constant force upon one another so that under the above-mentioned circumstances a perfectly vacuum-tight and reliable mounting of bulb and base can hardly be obtained.

According to the invention, this disadvantage can be completely avoided if in an electric dis- 2 bulb by means of an insulating member, the system has two or more extended supports which are free to move through holes provided in the,

said centering member, measures being taken to prevent this member from sliding upwards. Prior to the insertion of the electrode system into the bulb, first the said centering member is arranged within the bulb at the point desired; owing to the means provided to prevent displacement, for example owing to the presence of a groove in the wall of the bulb or to a reduction of the diameter of this wall, the said centering member is prevented from sliding further upward in the bulb when the continued supports are inserted in the holes of this member. In contrast to the commonly used constructions the said centering member is consequently not rigidly connected with the electrode system. Since upon displacement of the bulb with respect to the base in uniting bulb and base the said centering member need no longer be displaced and the extended supports are free to move up and down in the holes provided in this member, it is possible exactly to determine the force with which the bulb is pressed upon the edge of the base when bulb and base are being united, so that a reliable connection between bulb and base is obtained. After the bulb and base have been mounted, the centering member is enclosed between the electrode systems and the said groove or bulb portion of reduced diameter.

In order that the invention will be more clearly understood and readily carried into effect, it will now be explained more fully with respect to the accompanying drawing in which Fig. 1 illustrates a tube according to the invention in section, and Fig. 2 is a sectional view, with parts broken away, of another embodiment of the invention. Fig. 3 shows in cross-section a further embodiment of the invention.

In the Fig. 1 of drawing, I denotes an electrode system mounted by means of pins 3 on a base 2, said system being provided with a few extended supports 4. At 6 the bulb 5 exhibits a narrowed portion so that a dome is formed. Instead thereof, as shown in Fig. 2, it is alternatively possible to utilize a completely or incompletely circular groove 9. In the present case the bulb 5 is secured to the base by means of glaze I.

The bulb 5 comprises a centering member, for example a plate 8 of mica; when the bulb 5 is slid over the system I the extended supports 4 pass through holes provided in the member 8, the dome 6 preventing the member 8 from moving upwards. After the glaze 1 has been heated, the

bulb 5 is pressed with a determined slight pressure into the glaze I, the member 6 causing no trouble since the rods 4 are free to slide up and down in the holes of this member. With the use of glaze the weight of the bulb is in many cases sufiicient for exerting this pressure. If desired, the supports may be insulated from the electrodes so that any danger of the wall of the bulb becoming charged is avoided. The invention may be carried out in all those cases in which trouble is experienced from a clamping member when two parts required to be secured to one another by sealing or by means of cement, glaze or enamel, are placed upon one another with a determined pressure. Alternatively, both the base 2 and part of the bulb 5 may consist of metal. If use is made of a bulb in which the centering member is supported already in a dome, a second dome may be provided for carrying out the invention.

In Fig. 3 the centering member 8 is shown clamped in a narrow portion 10 of the bulb 5 and. a second narrowed portion ll prevents the centering member from sliding upwards.

What I claim is:

1. An electric discharge tube comprising a bulb,

an electrode system in said bulb and provided with at least two extended supporting members, a base carrying the said electrode system and sealed to the said bulb, a centering membe in said bulb and positioned adjacent the upper end thereof, means defining apertures in the said centering member, the said extended supporting members slidingly engaging the said aperture means to position the said electrode system in the said bulb, and means on said bulb for preventing said centering member from upward movement in said bulb.

2. An electric discharge tube comprising a bulb, an electrode system in said bulb and provided with at least two extended supporting members, a base carrying the said electrode system and sealed to the said bulb, a centering member in said bulb and positioned adjacent the upper end thereof, means defining apertures in the said centering member, the said extended supporting members slidingly engaging the said aperture means to position the said electrode system in the said bulb, and a groove on said bulb for prevent- 4 ing said centering member from upward move-'- ment in said bulb. I

3. An electric discharge tube comprising a bulb, an electrode system in said bulb and provided with at least two extended supporting members, a base carrying the said electrode system and sealed to the said bulb, a centering member in said bulb and positioned adjacent the upper end thereof, means defining apertures in the said centering member, the said extended supporting members slidingly engaging the said aperture means to position the said electrode system in the said bulb, and a narrowed top portion on said bulb for preventing said centering member from upward movement in said bulb.

4. An electric discharge tube comprising a bulb, an electrode system in said bulb and provided with at least two extended supporting members, a base carrying the said electrode system and sealed to the said bulb, a centering member in said bulb and positioned adjacent the upper end thereof, means defining apertures in the said centering member, the said extended supporting members slidingly engaging the said aperture means to position the said electrode system in the said bulb, a narrowed portion in said bulb near the top thereof for mounting the centering member therein, and a second narrowed portion above said first one for preventing said centering member from upward movement in said bulb.

CORNELIS FREDERIK VEENEMANS.

REFERENQES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,949,396 Wade Feb. 2'7, 1934 1,963,008 Weeks June 12, 1934 2,085,231 Rothe June 29, 1937 2,194,432 Pomfrett Mar. 19, 1940 2,262,901 Murphy Nov. 18, 1941 2,284,554 Krim Feb. 24, 1942 2,296,579 Seelen Sept. 22, 1942 2,344,931 Herzog et a1 Mar. 21, 1944 2,354,946 Cohen Aug. 1, 1944 2,380,496 Beard July 31, 1945 

